A side turn signal lamp integrated with a side mirror of a vehicle has been known in the related art. The side turn signal lamp is provided inside an elongated opening formed in a housing of the side mirror.
Japanese Patent Laid-Open Publication No. 2011-54523 discloses a side turn signal lamp in which a light guide lens is disposed along an opening. In the side turn signal lamp, the light guide lens has a light incident end face on which a light emitted from an LED serving as a light source is efficiently incident, and a light emitting portion provided in the vicinity of the distal end portion at the front side of a main body of the light guide lens. The light emitting portion is configured such that a part of the light incident on the main body of the light guide lens is emitted to the oblique back side of the vehicle. The main body of the light guide lens is formed to have a thickness gradually decreasing from the base end side to the distal end side.